J Interdiscipl Histopathol 2013; 1(5): 274-279 ISSN: 2146-8362

Case Report

A Case of Brucellosis Associated With Histiocytic Necrotizing Lymphadenitis: A Diagnostic Pitfall

Nicole Dalton Wheeler1, Marian Rollins-Raval2,3, Steven H. Swerdlow3, Swati Modi4, Kimberly Liang4, Robyn T. Domsic4, and Kathleen R. Sheridan1

1Department of Infectious , University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA 2Department of and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599-7525, USA 3Division of , Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213, USA 4Division of Rheumatology and Clinical Immunology, University of Pittsburgh Medical Center, Pittsburgh, PA 15261, USA

Received: June 26, 2013 Abstract Accepted: July 22, 2013 Human cases of brucellosis are rare in the United States and difficult to diagnose. We report a case of a young female who underwent a diagnostic investigation of Published Online: July 24, 2013 fever of unknown origin, which included a lymph node biopsy. The biopsy was DOI: 10.5455/jihp.20130722113848 consistent with Kikuchi’s , or histiocytic necrotizing lymphadenitis, an entity where the major differential diagnosis is systemic lupus erythematosus. Corresponding Authors: Interestingly, serologic studies supported the diagnosis of brucellosis. Brucellosis Nicole Dalton Wheeler, MD has rarely been associated with histiocytic necrotizing lymphadenitis. This Kathleen Sheridan, MD association has never been reported in the United States, thus suggesting that Department of Infectious Diseases, University of Pittsburgh Medical Center, brucellosis should be considered in the differential for histiocytic necrotizing 3601 Fifth Avenue, 3rd floor Falk Medical lymphadenitis, along with lupus-like autoimmune disease. As the prognosis and Building, Suite 3A, Pittsburgh, PA 15213, treatment of histiocytic necrotizing lymphadenitis, brucellosis, and systemic lupus USA erythematosus are distinct, it is important to differentiate these entities. [email protected] [email protected] Keywords: Brucellosis; Kikuchi’s disease; histiocytic necrotizing lymphadenitis; systemic lupus erythematosus © 2013 GESDAV

INTRODUCTION focal complication is osteoarticular involvement, such as reactive arthritis, sacroiliitis, or spondylitis [2]. Human brucellosis, though rare in the U.S. with only 100 cases per year reported [1], is the most common When there is a high index of suspicion, diagnosis is zoonosis in the world [2]. Humans can acquire the best made by culture of the organism from blood, or disease by: ingestion of raw dairy products or infected bone marrow, though poorly sensitive. A rise in meat; by contact with secretions or blood of antibody titers is suggestive of disease, but falsely chronically-infected animals; or by inhalation of positive results are possible. A positive serum contaminated aerosols. The incubation period is usually agglutination test may be more specific [4]. A lymph two to four weeks, followed by an onset that can be node biopsy is not a routine part of the diagnostic acute or insidious [3]. The most common clinical work-up, and the histologic findings are not well manifestations of acute brucellosis are non-specific, described in the literature. and include intermittent fevers, arthralgias, and fatigue. We report a case of fever of unknown origin in which However, the spectrum of disease includes serologic studies supported a diagnosis of brucellosis asymptomatic to exhibiting diverse signs and and lymph node biopsy showed histology consistent symptoms related to almost any organ system [4]. with histiocytic necrotizing lymphadenitis, which has Endocarditis is a relatively rare complication (<2%), rarely been associated with brucellosis. but accounts for the most deaths [3]. The most common

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CASE PRESENTATION plasma cells and histiocytes. The necrotic areas showed mostly necrotic cellular debris with admixed An active, otherwise healthy, 22-year-old female was lymphocytes and histiocytes, including occasional admitted for further work-up of fever of unknown histiocytes with crescentic nuclei (Figure 1B). origin. She has a past medical history of acne, treated Particularly the edge of the necrotic areas showed a with doxycycline 50mg daily. She lives in central focally prominent population that appeared to represent Pennsylvania, with no history of international travel. plasmacytoid dendritic cells (Figure 1C). Paraffin She was working in a laboratory that studies New section immunohistochemical stains demonstrated B- Zealand mud snails. Otherwise, she had no farm animal cells predominantly in follicles, as well as numerous T- contact and did not ingest any unpasteurized milk or cells mostly outside of the follicles. There were cheese. There was no family history of autoimmunity prominent aggregates of CD123 positive plasmacytoid or immunodeficiency. dendritic cells, particularly at the periphery of the Approximately two months prior to her presentation, necrotic regions (Figure 1D). There were numerous she developed fevers, fatigue, malaise, myalgias, right CD4 positive cells, outside of the necrotic areas, but upper quadrant pain and weight loss. Given her fevers fewer CD4 positive lymphocytes within the necrotic and findings of a new pancytopenia, she was admitted areas (Figure 1E). In contrast, CD8 positivity was more to a local hospital. The work-up was largely prominent within the necrotic areas, highlighting some unremarkable, including: for hepatitis A/B/C, viable cells as well as debris (Figure 1F). The Epstein-Barr Virus (EBV), Cytomegalovirus, and numerous CD68 positive histiocytes, concentrated in Lyme disease; Tuberculin skin test; antistreptolysin O and around the necrotic areas, were also titer; and a transthoracic echocardiogram. Contrast- myeloperoxidase positive, but there were only rare enhanced CT of the abdomen and pelvis revealed myeloperoxidase positive neutrophils (Figures 1G-H). mesenteric lymphadenopathy. She was transferred to Immunohistochemical stains for cytomegalovirus our institution five days later for further management. (CMV), Bartonella henselae and herpes simplex virus 1 and 2 were negative. AFB and Grocott stains were On examination, she was febrile to 39.3 °C, but other negative for acid fast bacilli and fungal organisms, vital signs were within normal limits. She had tender respectively. There were no hematoxylin bodies or cervical lymphadenopathy. Her heart rate was irregular evidence of the Azzopardi phenomenon identified. with skipped beats, and without murmur. Upon examination of her abdomen, there was right upper quadrant tenderness and hepatomegaly, without Table 1: Select laboratory values of the patient obtained at rebound or guarding. Her musculoskeletal exam admission. revealed bilateral first and second metacarpophalangeal Patient value Reference range joints that were mildly full and tender to palpation, with WBC 1,000/L 3,800 – 10,600 a patch of overlying erythema, as well as tender ankles. The remainder of the physical examination was normal. Neutrophils 54% 44 - 77% On admission, the patient had pancytopenia and Bands 7% 0 - 5% elevated liver function tests, as well as a borderline Lymphocytes 31% 13 - 44% positive anti-histone antibody (Table 1). Her blood Monocytes 7% 4 - 13% chemistry panel was normal. Blood cultures drawn Atypical 1% 0% while already on antibiotics were negative. She had lymphocytes first degree atrioventricular block on admission EKG that progressed to second degree heart block on Hemoglobin 7.9 gm/dL 11.6 - 14.6 hospital day 5. Results of transthoracic Platelets 121,000/L 156,000 – 369,000 echocardiography and cardiac MRI showed no Creatinine 0.7 mg/dL 0.5 - 1.4 evidence of myocarditis or endocarditis. ALT 82 IU/L 14 - 54 She underwent cervical lymph node biopsy on hospital AST 126 IU/L 15 - 41 day 6 (Figure 1 A-H). Grossly, the left cervical lymph node biopsy showed areas of tan tissue juxtaposed with Bilirubin 0.6 mg/dL 0.3 - 1.5 areas of yellow and apparently hemorrhagic areas. The Alkaline 61 IU/L 38 - 126 histologic sections demonstrated a reactive-appearing Phosphatase lymph node with areas of extensive without HIV Antibody negative negative suppuration, but with abundant and debris Anti-histone 1.2 U <1.0 (Figure 1A). The viable areas showed follicles and antibody otherwise a heterogeneous mixture of small lymphocytes, occasional transformed lymphocytes,

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Figure 1: Cervical lymph node biopsy. A: A low magnification image demonstrates a reactive lymph node with areas of extensive eosinophilic necrosis. B: The necrotic areas showed some lymphoid cells and histiocytes, including some with crescentic nuclei but note the absence of neutrophils. C: The following immunohistologic stains (D-H) demonstrates this region of the histologic section with the necrotic area at the top of the image. D: CD123 highlights moderately numerous plasmacytoid dendritic cells at the periphery of the necrotic area. E: There were many CD4 positive T-lymphocytes in the more viable lymph node with fewer in the necrotic area. Many histiocytes are also more weakly CD4 positive. F: In contrast, there were few CD8 positive cells in the more viable area with more numerous positive cells and debris in the necrotic area. G: The necrotic area also demonstrated moderately numerous CD68 positive histiocytes. Inset: Crescentic macrophage is positive for CD 68. H: The histiocytes were also positive for myeloperoxidase (MPO). Inset: Crescentic macrophage is positive for MPO (A: H&E, 20x; B:H&E, 1000x; C;H&E 100x; D-H: immunostain with hematoxylin counterstain, 100x; insets: 1000x).

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On hospital day 8, her Brucella IgM was reported as weeks later, her Brucella titers had increased to IgM weakly positive with a value of 1.01 and IgG was 0.53 1.88 and IgG 1.04. Her pancytopenia and AV block [reference range: <0.80 not detected, 0.80-1.09 completely resolved, as did her fevers, joint pains, and equivocal, 1.10 or greater antibody detected (Figure abdominal pain. She was continued on doxycycline and 2)]. She was started on treatment for acute brucellosis rifampin for an additional four months given her with doxycycline 100mg twice daily, rifampin 300mg multiple organ involvement. Three months later, her twice daily, and IV gentamicin 5mg/kg daily. Two Brucella titers were: IgM 0.64 and IgG 1.43.

Figure 2: Depiction of early Brucella IgM and late IgG increase after antibiotic treatment.

DISCUSSION antibody titers trended as expected for an acute with recovery. However, she also had some This case illustrates a diagnostic dilemma regarding the clinical features that are atypical for brucellosis, possible clinical and histopathologic overlap between including pleuritic chest pain, symmetric small joint brucellosis and histiocytic necrotizing lymphadenitis polyarthritis, and weakly positive anti-histone antibody, (HNL). Brucellosis is frequently misdiagnosed, given suggestive of possible early connective tissue disease. its lack of specific symptoms, variety of presentations, Yet serologic autoimmune laboratory abnormalities and rarity in many parts of the world. Diagnosis is also have been reported in active brucellosis [5, 6], difficult because of poor sensitivity of culture and lack including weakly positive ANA (25%) and rheumatoid of a definitive diagnostic test. In this case, her prior factor (38%) [7]. Brucella has also been known to receipt of doxycycline may have inhibited the growth cause reactive arthritis [2, 7, 8]. of Brucella. Although we were unable to make a definitive diagnosis, many of the patient’s clinical Lymph node biopsy is not routine, thus the full features were compatible with this disease. An spectrum of morphologic changes seen in the lymph evaluation of her clinical findings revealed nodes of patients with brucellosis are not well- pancytopenia, hepatomegaly, lymphadenopathy, documented. It is thought that Brucella infection arthritis, and progressive cardiac conduction delay typically takes one of two forms. The first has which all can be manifestations of acute brucellosis. sometimes been described as showing a “simple form,” Her symptoms, pancytopenia, and heart block resolved with follicular , sinus histiocytosis, or on antibiotic treatment for brucellosis. In addition, her expanded areas of monocytoid B-cells, with increased

277 J Interdiscipl Histopathol 2013; 1(5): 274-279 Brucellosis associated with histiocytic necrotizing lymphadenitis numbers of plasma cells. There may also be a prognosis and treatments are distinct. However, proliferation of large, pale cells between the follicles. brucellosis can be a difficult diagnosis to confirm, and The second form, seen more frequently, may manifest this patient may have two concurrent diagnoses or may with numerous clusters of epithelioid histiocytes, at still develop lupus or connective tissue disease. Future times becoming confluent and rarely encroaching upon studies with longer follow-up of brucellosis cases may germinal centers [9]. For this patient, the lymph node help clarify whether HNL or other findings demonstrate a necrotizing lymphadenitis that mimicking HNL leads to development of systemic has many features of HNL or possibly lupus, including lupus erythematosus, despite appropriate antimicrobial extensive areas of necrosis without suppuration. treatment. However, the patient’s marked peripheral blood neutropenia may contribute to the lack of neutrophils in this setting. ACKNOWLEDGEMENTS Only two cases of brucellosis associated with the We would like to thank the Infectious Disease division histopathologic findings of HNL have been described at the University of Pittsburgh Medical Center for in the literature [10, 11]. In one case report, the authors support and funding, and also thank Katherine K. describe that the patient, a 43-year-old male cattler, had Rogers for grammatical review of the manuscript. a history of brucellosis diagnosed three months prior to his admission for fever, arthralgias, night sweats, painful enlargement of cervical and axillary lymph CONFLICTS OF INTEREST nodes, and hepatosplenomegaly. In order to evaluate the patient’s persistent fever in light of decreasing titers Authors declare that they have no conflicts and and negative cultures, a lymph node biopsy was disclosures. performed, showing findings characteristic of HNL, REFERENCES including paracortical areas with “karyorrhectic debris seen in both blastic and necrotizing areas, in a patchy 1. Brucellosis: Technical Information. 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